Filters are devices used for filtering the liquid containing impurities. Particularly in the agricultural irrigation field, filtering the large particles in water is required to obtain purer irrigation water. The existing laminated filter basically consists of some major parts, such as housing, lamination, lamination support, pre-pressing spring, etc. The function of the pre-pressing spring is to provide a force pre-pressing the laminations, so that the laminations are combined closely. When pressurized water passes through the gap between the laminations, the particles in the water will be filtered.
The prior art, such as a laminated filter disclosed by the Chinese Patent Publication CN201357011, a micro-irrigation backflush laminated filter disclosed by the Chinese Patent Publication CN2875559 and an agricultural micro-irrigation system laminated filter disclosed by the Chinese Patent Publication CN202724814U, all adopt pre-pressing spring to provide the pressing force between the laminations.
During using filters, all the parts in the housing are immersed in water. When irrigation is not required, the parts in the housing are exposed in air. If made from carbon steel, the pre-pressing spring will lose efficacy in a short time due to corrosion. If made from stainless steel, the pre-pressing spring will lose efficacy in a short time due to elasticity attenuation. The consequence of the spring losing efficacy is that no pressing force exists between the laminations and the filter will lose the function to filter.